<!DOCTYPE html>
<html lang="zh-Hans">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title></title>
  <script src="./xuqifen.js"></script>
</head>
<body onload="ymd()">
<form action="">
  <select name="years" id="years" onchange="selectYmd()"></select>年
  <select name="months" id="months" onchange="selectYmd()"></select>月
  <select name="dates" id="dates"></select>日
  test
</form>
</body>

</html>